In many industries, component parts used in the assembly of a larger item of equipment are often shipped to an assembler in either disposable or recyclable packages. Typically, the manufacturer removes the component from the shipping package, and places the component into a processing fixture. The processing fixture holds the component sufficiently rigid such that certain processes can be performed on the component. Removal of a component from it's shipping tray and placement into the processing fixture can be done either by automation or manually.
While the foregoing describes a common method of assembling component parts into a larger whole, it also describes a process infused with complexity and cost. If the components are removed with automation, the capital cost of such equipment and related overhead adds cost to the manufacturer. If the components are removed manually, the labor rate of the operators performing this act also increases the manufacturer's cost. Further, in many cases, the processing fixtures employed by manufacturers are complex and costly. Finally, where the components are fragile or otherwise easily damaged, the removal of the component from its shipping package and its installation into a processing fixture—whether by hand or through some automated procedure—may result in costly component damage from the handling of the component.
As an illustration of the foregoing methods and processes and the problems associated therewith, the hard disk drive industry can be considered. A hard disk drive is the device most predominantly used for long term memory/data storage in modern computer systems. In overview, a hard disk drive comprises a disk that is rotated at high speeds. The disk has a magnetic coating or read/write media that can be selectively magnetized with the application of a magnetic field thereto. A “read/write” device, commonly called a head, is attached to and held closely adjacent the disk by a head suspension assembly and is moved radially relative to the rotating disk, that is, from the edge of the disk toward the center and back. Electric current is provided to the head which creates and applies a magnetic field to the disk as the head moves relative thereto. Selective areas of the disk are preferentially magnetized as the magnetic field is applied to the disk. Each magnetized area consists of a north and south pole selectively oriented in one of two preferred directions. Magnetized areas having a north pole pointing in one of the two direction are designated as a “0” and in the other direction as a “1.” In this way the binary language of computers consisting of zeroes and ones is assembled on the magnetized disk coating and data and programs, which comprise zeroes and ones in binary computer language, are stored on the hard disk.
Continuing with the example of the disk drive industry, head suspension assemblies are shipped in disposable vacuum-formed trays to manufacturers who may attach the read/write head thereto. The manufacturers remove the head suspension assembly from it's shipping tray and place it into an intricate processing fixture, referred to as a “head bond fixture.” Typically, head bond fixtures are precise, machined metal fixtures with several moving parts. Often times, these fixtures include a small clamping mechanism to hold the suspension assembly sufficiently rigid during the assembly process. The surface of the fixture which mates with the suspension assembly is ground to complex geometries with very tight tolerances, thus making them very costly. Once placed within the head bond fixture, the suspension assembly is held in such a manner that a read/write head can be bonded to it.
As in any industry, manufacturing costs in the hard disk drive industry are carefully monitored. The hard disk provides large amounts of storage capability at relatively low cost. As the technology continually matures, the storage density per unit of cost, that is, the quantity of data stored per dollar, is continuously increasing, as is the reliability of the hard disk and its related components, (collectively called the hard disk drive, hard drive, or disk drive) and the rate at which data can be transferred to and from the disk. That is, advancing hard disk technology is resulting in the storage of increasing amounts of information at decreasing unit costs. Yet, in spite of the rapid advance in storage technology, the technology continues to face cost pressures as competition in the marketplace intensifies and computer programs grow in size. It would be helpful if the cost pressures arising out of damage that occurs during the assembly process could be reduced as well as the cost pressures that result from labor or inflexible tooling intensive processes.
Head suspension assemblies are extremely fragile and susceptible to damage from handling such as that occurring during the assembly process. That is, the act of removing a head suspension assembly from it's packaging and installing it in a processing fixture can result in the destruction of the assembly or damage it so as to degrade seriously the suspension's later operational performance.
One source of possible damage to the components stems from electrostatic discharge (ESD) or electrical overstress (EOS), collectively referred to as ESD/EOS. ESD/EOS usually results from touching an object and causing a build-up of static charges. Prior to the time that the head suspension assembly is installed into a disk drive, the electrical interconnect is electrically connected to the read and write elements, but is not connected to the drive electronics. As a result, the individual conductors that make up the electrical interconnect, can easily be charged by stray voltages, thereby creating a voltage potential across the sensitive magnetoresistive or giant magnetoresistive read elements of the read/write head, which when discharged results in damaging current transients through the read element.
The components used in hard disk drives are small and continually decreasing in size. Consequently, any tolerance for ESD/EOS damage of the components during the assembly process is also continuously decreasing while their susceptibility to damage during assembly is increasing. The present methods of assembly, however, are the source for the creation of much static potential charge, whether through direct handling of the component parts or because of the human assemblers doing some normal activity such as shuffling their feet or wiping their brow. Minimizing the handling of the head suspension assembly is thus desirable, yet present packaging, transportation and assembly methods result in the need for an undesirable amount of such handling.
The small size of the components and their continually decreasing size also reduces any tolerance for misalignment of the components during the assembly process while increasing their susceptibility to damage during assembly. Current disk drive assembly includes expensive, labor intensive processes, particularly the assembly of the flex circuit to the suspension assembly. The labor intensive nature of the assembly process has several consequences. First, the labor increases the final cost of the assembled suspension. Second, because of the heavy use of labor in the assembly, there is a meaningful quantity of handling of the components by the assembler, which increases the likelihood of damage to the components. Third, the assemblers are limited in both the precision and speed with which the flex circuits can be assembled to the suspensions. Fourth, even though human assemblers are used, the assembly process is quite tooling intensive. Fifth, as the part geometries change as the technology advances, the costs also increase because of the need for new tooling in the assembly of the new parts; that is, the tooling used is either not adaptable or not readily adaptable to new part geometries.
Additional costs that are not included in calculation of the cost of the use of human assemblers are those of the consumer whose hard drive fails, perhaps due to damage to a component by a human assembler. Though data backups are always advised, such advice is often unheeded. When a hard drive fails the consumer may lose valuable data that is either not easily replaced or is replaced only at some cost in terms of time and effort, if not actual cash outlays.
Many of the foregoing deficiencies in the employment of human assemblers could be reduced or eliminated with a precision automated assembly apparatus and method for attaching flex circuits to suspensions. Automated assembly machines and methods should result in lower costs, reduced component handling and possible damage, and have greater flexibility to accommodate variations in component types, geometries and improved placement tolerances. Simple automation of the actual assembly of the flex circuit to the suspension will not, however, eliminate the problems associated with removing the components from their shipping trays and placing them in an assembly apparatus.
For the reasons discussed previously, there is a need for an inexpensive packaging tray that can also be utilized as a processing fixture. This approach has several advantages over the processes and apparatus described above. First, because the components need not be removed from the shipping tray during subsequent manufacturing processes, the likelihood of damage resulting from handling is significantly reduced. Second, the costs associated with the removal of the component from the shipping package are eliminated. Finally, this approach eliminates the need for costly processing fixtures.